US2025371691A1PendingUtilityA1

Device for diagnosing defect using model based on continual learning and method therefor

Assignee: DOOSAN ENERBILITY CO LTDPriority: May 28, 2024Filed: Mar 5, 2025Published: Dec 4, 2025
Est. expiryMay 28, 2044(~17.8 yrs left)· nominal 20-yr term from priority
G06T 2207/30168G06T 2207/20081G06T 2207/10116G06T 7/0002G06N 3/096G06T 2207/20084G01N 23/04G06N 20/00G06V 10/82G06V 10/774
59
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Claims

Abstract

Proposed are a device for diagnosing a defect using a model based on continual learning and a method therefor, and the method for diagnosing the defect includes a step of loading, by a training unit, a buffer training data set, which is training data selected according to a degree of influence on prediction performance of a current model from among a past training data set in the continual learning, a step of training the current model using the buffer training data set and a current training data set, and a step of detecting, by a detection unit, the defect in a radiographic image using the current model when the radiographic image is input.

Claims

exact text as granted — not AI-modified
What is claimed is: 
     
         1 . A method for diagnosing a defect, the method comprising:
 training, by a training unit, a current model using a buffer training data set previously stored in a buffer and a current training data set; and   detecting, by a detection unit, the defect in a radiographic image using the current model when the radiographic image is input.   
     
     
         2 . The method for  claim 1 , wherein the training of the current model comprises:
 loading, by the training unit, the buffer training data set, which is training data selected according to a degree of influence on prediction performance of the current model from among a past training data set in continual learning; and   training the current model using the buffer training data set and the current training data set.   
     
     
         3 . The method for  claim 1 , further comprising:
 calculating, by a switching unit, after the training of the current model, a degree of change from models trained in at least two previous training rounds of the current model in the continual learning to the current model;   determining, by the switching unit, whether the degree of change is greater than or equal to a reference value;   determining, by the switching unit, an update to the buffer training data set when the degree of change is greater than or equal to the reference value;   calculating, by an update unit, a degree of influence of each of data points in the current training data set on prediction performance of a future model when the future model to be trained in a next training round of the current model is trained using the current training data set in the continual learning; and   updating, by the update unit, the buffer training data set by selecting a predefined number of the data points in order of higher to lower degrees of influence.   
     
     
         4 . The method for  claim 3 , wherein the calculating of the degree of influence comprises:
 calculating, by the update unit, a plasticity score representing a first probability that a first prediction value of the current model and a second prediction value of the future model are different from each other for the data points in the current training data set;   calculating, by the update unit, a stability score representing a second probability that the first prediction value of the current model and a third prediction value of a first past model trained in a previous training round of the current model, are different from each other for the data points in the current training data set; and   determining, by the update unit, a weighted average of the plasticity score and the stability score as the degree of influence.   
     
     
         5 . The method for  claim 3 , wherein calculating a stability score is performed according to Equation 
       
         
           
             
               
                 
                   p 
                   ⁡ 
                   ( 
                   
                     
                       
                         y 
                         ^ 
                       
                       
                         t 
                         - 
                         1 
                       
                     
                     ≠ 
                     
                       
                         
                           y 
                           ^ 
                         
                         t 
                       
                       ⁢ 
                       
                         
                           ❘ 
                           "\[LeftBracketingBar]" 
                         
                         
                           x 
                           t 
                         
                       
                     
                   
                   ) 
                 
                 = 
                 
                   1 
                   - 
                   
                     p 
                     ⁡ 
                     ( 
                     
                       
                         
                           y 
                           ^ 
                         
                         n 
                         
                           t 
                           - 
                           1 
                         
                       
                       ⁢ 
                       
                         
                           ❘ 
                           "\[LeftBracketingBar]" 
                         
                         
                           
                             
                               y 
                               ^ 
                             
                             n 
                             t 
                           
                           , 
                           
                             x 
                             n 
                             t 
                           
                         
                       
                     
                     ) 
                   
                 
               
               , 
             
           
         
         wherein p(ŷ t−1 ≠ŷ t |x t ) denotes the stability score, 
       
       
         
           
             
               x 
               n 
               t 
             
           
         
       
       denotes the data points in the current training data set, 
       
         
           
             
               
                 y 
                 ^ 
               
               n 
               
                 t 
                 - 
                 1 
               
             
           
         
       
       denotes a first prediction value of a first past model, and 
       
         
           
             
               
                 y 
                 ^ 
               
               n 
               t 
             
           
         
       
       denotes a second prediction value of the current model. 
     
     
         6 . The method for  claim 3 , wherein calculating a plasticity score is performed according to Equation 
       
         
           
             
               
                 
                   p 
                   ⁡ 
                   ( 
                   
                     
                       
                         y 
                         ^ 
                       
                       
                         t 
                         + 
                         1 
                       
                     
                     ≠ 
                     
                       
                         
                           y 
                           ^ 
                         
                         t 
                       
                       ⁢ 
                       
                         
                           ❘ 
                           "\[LeftBracketingBar]" 
                         
                         
                           x 
                           t 
                         
                       
                     
                   
                   ) 
                 
                 = 
                 
                   1 
                   - 
                   
                     p 
                     ⁡ 
                     ( 
                     
                       
                         
                           y 
                           ^ 
                         
                         n 
                         
                           t 
                           + 
                           1 
                         
                       
                       ⁢ 
                       
                         
                           ❘ 
                           "\[LeftBracketingBar]" 
                         
                         
                           
                             
                               y 
                               ^ 
                             
                             n 
                             t 
                           
                           , 
                           
                             x 
                             n 
                             t 
                           
                         
                       
                     
                     ) 
                   
                 
               
               , 
             
           
         
         wherein p(ŷ t+1 ≠ŷ t |x t ) denotes the plasticity score, 
       
       
         
           
             
               x 
               n 
               t 
             
           
         
       
       denotes the data points in the current training data set, 
       
         
           
             
               
                 y 
                 ^ 
               
               n 
               
                 t 
                 + 
                 1 
               
             
           
         
       
       denotes a first prediction value of the future model, and 
       
         
           
             
               
                 y 
                 ^ 
               
               n 
               t 
             
           
         
       
       denotes a second prediction value of the current model. 
     
     
         7 . The method for  claim 6 , wherein the calculating of the plasticity score derives the prediction value of the future model according to Equation 
       
         
           
             
               
                 
                   p 
                   ⁡ 
                   ( 
                   
                     
                       
                         y 
                         ^ 
                       
                       
                         t 
                         + 
                         1 
                       
                     
                     ⁢ 
                     
                       
                         ❘ 
                         "\[LeftBracketingBar]" 
                       
                       
                         x 
                         t 
                       
                     
                   
                   ) 
                 
                 = 
                 
                   f 
                   ⁡ 
                   ( 
                   
                     
                       GP 
                       ⁡ 
                       ( 
                       
                         θ 
                         t 
                       
                       ) 
                     
                     , 
                     x 
                   
                   ) 
                 
               
               , 
             
           
         
         wherein 
       
       
         
           
             
               
                 y 
                 ^ 
               
               n 
               
                 t 
                 + 
                 1 
               
             
           
         
       
       denotes the first prediction value of the future model,
 x denotes the data points in the current training data set, and 
 GP(θ t ) denotes a gradient vector predicted by the future model through a gradient prediction model. 
 
     
     
         8 . The method for  claim 3 , wherein the calculating of the degree of influence is performed according to Equation 
       
         
           
             
               
                 
                   S 
                   i 
                 
                 = 
                 
                   
                     λ 
                     · 
                     
                       Plasticity 
                       i 
                     
                   
                   + 
                   
                     
                       ( 
                       
                         1 
                         - 
                         λ 
                       
                       ) 
                     
                     · 
                     
                       Stability 
                       i 
                     
                   
                 
               
               , 
             
           
         
         wherein S denotes the degree of influence, 
         i denotes an index of the data points in the current training data set, 
         λ denotes a weight, 
         Plasticity denotes a plasticity score, and 
         Stability denotes a stability score. 
       
     
     
         9 . The method for  claim 3 , wherein the calculating of the degree of change derives the degree of change according to a degree of similarity between:
 a first gradient vector representing a first change between a first weight vector of the current model and a second weight vector of a first past model trained in the previous training round of the current model, and   a second gradient vector representing a second change between the second weight vector of the first past model and a third weight vector of a second past model trained in a previous training round of the first past model.   
     
     
         10 . The method for  claim 9 , wherein the degree of similarity is calculated according to Equation 
       
         
           
             
               
                 CS 
                 = 
                 
                   
                     
                       g 
                       
                         t 
                         - 
                         1 
                       
                       T 
                     
                     ⁢ 
                     
                       g 
                       t 
                     
                   
                   
                     
                       
                          
                         
                           g 
                           
                             t 
                             - 
                             1 
                           
                         
                          
                       
                       2 
                     
                     ⁢ 
                     
                       
                          
                         
                           g 
                           t 
                         
                          
                       
                       2 
                     
                   
                 
               
               , 
             
           
         
         wherein CS denotes the degree of similarity, 
         g t  denotes the first gradient vector between the first weight vector of the current model and the second weight vector of the first past model, 
         g t−1  denotes the second gradient vector between the second weight vector of the first past model and the third weight vector of the second past model, and 
       
       
         
           
             
               g 
               
                 t 
                 - 
                 1 
               
               T 
             
           
         
       
       denotes a transpose vector of the second gradient vector. 
     
     
         11 . A device for diagnosing a defect, the device comprising:
 a training unit configured to train a current model using a buffer training data set previously stored in a buffer and a current training data set; and   a detection unit configured to detect the defect in a radiographic image using the current model when the radiographic image is input.   
     
     
         12 . The device of  claim 11 , wherein the training unit loads the buffer training data set, which is training data selected according to a degree of influence on prediction performance of the current model from among a past training data set in continual learning, and trains the current model using the buffer training data set and the current training data set. 
     
     
         13 . The device of  claim 11 , further comprising:
 a switching unit configured to:   calculate a degree of change from models trained in at least two previous training rounds of the current model in the continual learning to the current model;   determine whether the degree of change is greater than or equal to a reference value; and   determine an update to the buffer training data set when the degree of change is greater than or equal to the reference value, and   an update unit configured to:   calculate a degree of influence of each of data points in the current training data set on prediction performance of a future model when the future model to be trained in a next training round of the current model is trained using the current training data set in the continual learning; and   update the buffer training data set by selecting a predefined number of the data points in order of higher to lower degrees of influence.   
     
     
         14 . The device of  claim 13 , wherein the update unit calculates a plasticity score representing a first probability that a first prediction value of the current model and a second prediction value of the future model are different from each other for the data points in the current training data set, calculates a stability score representing a second probability that the first prediction value of the current model and a third prediction value of a first past model trained in a previous training round of the current model, are different from each other for the data points in the current training data set, and determines a weighted average of the plasticity score and the stability score as the degree of influence. 
     
     
         15 . The device of  claim 13 , wherein the update unit calculates a stability score according to
 Equation   
       
         
           
             
               
                 
                   p 
                   ⁡ 
                   ( 
                   
                     
                       
                         y 
                         ^ 
                       
                       
                         t 
                         - 
                         1 
                       
                     
                     ≠ 
                     
                       
                         
                           y 
                           ^ 
                         
                         t 
                       
                       ⁢ 
                       
                         
                           ❘ 
                           "\[LeftBracketingBar]" 
                         
                         
                           x 
                           t 
                         
                       
                     
                   
                   ) 
                 
                 = 
                 
                   1 
                   - 
                   
                     p 
                     ⁡ 
                     ( 
                     
                       
                         
                           y 
                           ^ 
                         
                         n 
                         
                           t 
                           - 
                           1 
                         
                       
                       ⁢ 
                       
                         
                           ❘ 
                           "\[LeftBracketingBar]" 
                         
                         
                           
                             
                               y 
                               ^ 
                             
                             n 
                             t 
                           
                           , 
                           
                             x 
                             n 
                             t 
                           
                         
                       
                     
                     ) 
                   
                 
               
               , 
             
           
         
         wherein p(ŷ t−1 ≠ŷ t |x t ) denotes the stability score, 
       
       
         
           
             
               x 
               n 
               t 
             
           
         
       
       denotes the data points in the current training data set, 
       
         
           
             
               
                 y 
                 ^ 
               
               n 
               
                 t 
                 - 
                 1 
               
             
           
         
       
       denotes a first prediction value of a first past model, and 
       
         
           
             
               
                 y 
                 ^ 
               
               n 
               t 
             
           
         
       
       denotes a second prediction value of the current model. 
     
     
         16 . The device of  claim 13 , wherein the update unit calculates a plasticity score according to
 Equation   
       
         
           
             
               
                 
                   p 
                   ⁡ 
                   ( 
                   
                     
                       
                         y 
                         ^ 
                       
                       
                         t 
                         + 
                         1 
                       
                     
                     ≠ 
                     
                       
                         
                           y 
                           ^ 
                         
                         t 
                       
                       ⁢ 
                       
                         
                           ❘ 
                           "\[LeftBracketingBar]" 
                         
                         
                           x 
                           t 
                         
                       
                     
                   
                   ) 
                 
                 = 
                 
                   1 
                   - 
                   
                     p 
                     ⁡ 
                     ( 
                     
                       
                         
                           y 
                           ^ 
                         
                         n 
                         
                           t 
                           + 
                           1 
                         
                       
                       ⁢ 
                       
                         
                           ❘ 
                           "\[LeftBracketingBar]" 
                         
                         
                           
                             
                               y 
                               ^ 
                             
                             n 
                             t 
                           
                           , 
                           
                             x 
                             n 
                             t 
                           
                         
                       
                     
                     ) 
                   
                 
               
               , 
             
           
         
         wherein p(ŷ t+1 ≠ŷ t |x t ) denotes the plasticity score, 
       
       
         
           
             
               x 
               n 
               t 
             
           
         
       
       denotes the data points in the current training data set, 
       
         
           
             
               
                 y 
                 ^ 
               
               n 
               
                 t 
                 + 
                 1 
               
             
           
         
       
       denotes a first prediction value of the future model, and 
       
         
           
             
               
                 y 
                 ^ 
               
               n 
               t 
             
           
         
       
       denotes a second prediction value of the current model. 
     
     
         17 . The device of  claim 16 , wherein the update unit derives the prediction value of the future model according to
 Equation   
       
         
           
             
               
                 
                   p 
                   ⁡ 
                   ( 
                   
                     
                       
                         y 
                         ^ 
                       
                       
                         t 
                         + 
                         1 
                       
                     
                     ⁢ 
                     
                       
                         ❘ 
                         "\[LeftBracketingBar]" 
                       
                       
                         x 
                         t 
                       
                     
                   
                   ) 
                 
                 = 
                 
                   f 
                   ⁡ 
                   ( 
                   
                     
                       GP 
                       ⁡ 
                       ( 
                       
                         
                           θ 
                             
                         
                         t 
                       
                       ) 
                     
                     , 
                     x 
                   
                   ) 
                 
               
               , 
             
           
         
         wherein 
       
       
         
           
             
               
                 y 
                 ^ 
               
               n 
               
                 t 
                 + 
                 1 
               
             
           
         
       
       denotes the first prediction value of the future model,
 x denotes the data points in the current training data set, and 
 GP(θ t ) denotes a gradient vector predicted by the future model through a gradient prediction model. 
 
     
     
         18 . The device of  claim 13 , wherein the update unit calculates the degree of influence according to
 Equation   
       
         
           
             
               
                 
                   S 
                   i 
                 
                 = 
                 
                   
                     λ 
                     · 
                     
                       Plasticity 
                       i 
                     
                   
                   + 
                   
                     
                       ( 
                       
                         1 
                         - 
                         λ 
                       
                       ) 
                     
                     · 
                     
                       Stability 
                       i 
                     
                   
                 
               
               , 
             
           
         
         wherein S denotes the degree of influence, 
         i denotes an index of the data points in the current training data set, 
         λ denotes a weight, 
         Plasticity denotes a plasticity score, and 
         Stability denotes a stability score. 
       
     
     
         19 . The device of  claim 13 , wherein the switching unit derives the degree of change according to the degree of similarity between:
 a first gradient vector representing a first change between a first weight vector of the current model and a second weight vector of a first past model trained in the previous training round of the current model, and   a second gradient vector representing a second change between the second weight vector of the first past model and a third weight vector of a second past model trained in a previous training round of the first past model.   
     
     
         20 . The device of  claim 19 , wherein the switching unit calculates the degree of similarity according to
 Equation   
       
         
           
             
               
                 CS 
                 = 
                 
                   
                     
                       g 
                       
                         t 
                         - 
                         1 
                       
                       T 
                     
                     ⁢ 
                     
                       g 
                       t 
                     
                   
                   
                     
                       
                          
                         
                           g 
                           
                             t 
                             - 
                             1 
                           
                         
                          
                       
                       2 
                     
                     ⁢ 
                     
                       
                          
                         
                           g 
                           t 
                         
                          
                       
                       2 
                     
                   
                 
               
               , 
             
           
         
         wherein CS denotes the degree of similarity, 
         g t  denotes the first gradient vector between the first weight vector of the current model and the second weight vector of the first past model, 
         g t−1  denotes the second gradient vector between the second weight vector of the first past model and the third weight vector of the second past model, and 
       
       
         
           
             
               g 
               
                 t 
                 - 
                 1 
               
               T 
             
           
         
       
       denotes a transpose vector of the second gradient vector.

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